(1) Field of the Invention
The present invention relates to a structural section capable of withstanding high pressures and being relatively easy to manufacture.
(2) Description of the Prior Art
Underwater vehicles which operate at significant depth, such as torpedoes, targets and unmanned undersea vehicles employ a rib-stiffened, cylindrical structural element 10 as shown in FIG. 1. Structural element 10 has a clamped joint 12A and 12B at each end. These structural elements are one piece and are generally machined from a single aluminum forging (traditionally 6061-T6 or 7075-T6). Structural element 10 has a skin 14 with ribs 16 formed at intervals along the length of structural element 10. Female clamped joint 12A is shown in detail in FIG. 2A, and male clamped joint 12B is shown in FIG. 2B. When two structural elements 10 are joined together, inside shoulder 18 of joint 12B is positioned inside mating sleeve 20 of joint 12A. A joint band, not shown, is then positioned about the joint, extending into joint band grooves 22.
The ribs and joint design consume internal volume and reduce the clear bore through the hulls. In typical vehicles, a 21″ outside diameter hull is reduced to 18.5″ or less. Everything inside the structural element must pass through the narrowest diameter. This results in a 22% volume reduction. Unless an internal rail and carriage system is employed, maintenance access to components within the hull is limited to what can be reached via the ends. Significant disassembly is often required to repair a component centrally located within the hull.